Recent content by evan9162

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  1. E

    Cree MC-E Images

    I think Cree saw the P7 and said "17 bond wires? WE CAN DO BETTER THAN THAT! How about 24? Suck on that, Seoul!"
  2. E

    Luminous efficacy improves with excess current??

    Look at the column headers. The left is "Minimum". The right is "Typical". They aren't referring to the same thing.
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    Quad cree led !

    The info for the first link has got to be a mistake. The P4 is already 6.9C/W - I can't see why the P7 would be higher. I wonder if they mixed up some of the specs with another product (i.e. copied the table form over from an existing web page, and didn't change all the fields). At any rate...
  4. E

    Quad cree led !

    A single die won't have a thermal resistance of 3 C/W. The thermal resistance is the rating when all 4 dies are powered. A single die will still have a thermal resistance of probably 8 C/W. This and the Seoul P7 get a lower thermal resistance because each watt of input power is now spread...
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    100K hour life vaporware

    That show was bad. Really bad.
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    100K hour life vaporware

    He's probably referencing this data: http://www.luxeon.com/pdfs/AB07.PDF ... page 3. But if you look here: http://www.luxeon.com/pdfs/RD25.pdf On page 4, they have a graph that clearly shows test data out to almost 20K hours, and this was data from 2003. So he's either referring to data on 5mm...
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    100K hour life vaporware

    Just who do you think owns Lumileds?
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    Seoul P7 low voltage pictures

    It's good that they appear pretty even at higher current levels - the crooked die is kinda funny though.
  9. E

    Seoul P7 low voltage pictures

    The dies in the P7 are in parallel, not in series. Plus, they're supposed to be closely matched dies to avoid current inbalance and uneven brightness in the beam. The most likely answer is that at low voltages (and hence, low current), there is a significant current imbalance. HOWEVER, that...
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    Seoul P7 low voltage pictures

    I think that many instances of this phenomenon on the Lux V were caused by something other than uneven current sharing due to mismatched dies...the most likely thing that it's a side effect of the series/parallel arrangement, and some leakage current through the silicon submount...
  11. E

    Seoul P7 low voltage pictures

    To answer your question: Yes - the brighter dies have a lower Vf (at a given current), and thus, more current is flowing through them. That's a pretty significant imbalance at that current level (easily 3-4x the current going through the brighter ones). Not sure how that would translate into...
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    Why is this circuit not working properly?!?

    You can only do that with the LED tester because it's a constant current supply. If you did that with any other kind of power supply (or battery even), you risk destroying the supply, your meter, or both. The measurements you get from the LED tester should be accurate - it uses a constant...
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    Why is this circuit not working properly?!?

    When you're measuring current, does the LED that you're measuring at go out? If so, you're bypassing that LED with your current meter, essentially removing one from the circuit. Now there are only 4 LEDs in series, not 5. So naturally, current will increase. A meter in current mode looks...
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    7ah Ni-Cad D cells

    Re: 7 Ah NiCd D cells I bought one of these from Amondotech a while ago. It actually tested out to about 7Ah (using my Triton to charge/discharge). I charged it at 2A once, and it leaked all over the place. So I think that these will genuinely produce 7Ah of capacity, but since they're...
  15. E

    Z-Power P7 Series - World’s Highest Brightness of 900 lm at 10-watt

    It's not really a big leap in thermal resistance at all. First, the Lux V emitter was 8C/W, not 11C/w (the star was 11C/W) Second, slapping down 4 dies is going to improve thermal resistance even if you don't change a thing about each die. In fact, Seoul wouldn't have to change a thing to...
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